The invention relates to a deflection pulley or a tensioning device for a traction element, such as a belt, band, or chain, with a tensioning arm, which is arranged on a machine part so that it can pivot and on which a deflection pulley for the traction element is mounted so that it can rotate via a roller bearing, and with a protective cap, which covers the bearing region of the deflection pulley and which is secured on the deflection pulley with a non-positive and/or positive fit connection.
With the protective cap of a deflection pulley or a tensioning device, the bearing region of the deflection pulley should be protected against the penetration of contaminants and sprayed water.
It is already known not to connect the protective cap of the deflection pulley to the deflection pulley with a non-positive or positive fit connection, but instead to construct it as a protective plate, which forms an annular gap with the deflection pulley. In this way, between the rotating deflection pulley and the protective plate fixed relative to the deflection pulley, a labyrinth seal is created, which, however, still does not allow the desired high sealing effect.
It is also known to form a rim for the detachable mounting of the protective cap on the deflection pulley with a steel sheave. Here, however, e.g., raising the edge of the rim through roll deformation requires an additional processing step in the manufacturing process of the deflection pulley, which results in extra costs.
The publication DE 100 24 318 A1 shows a tensioning device of the type noted above. As emerges there from FIG. 1 of the drawing, a protective cap is set axially on a hub of the deflection pulley and secured there with a friction fit connection. For such an arrangement with a steel sheave, it is also known to form a snap-in groove on the hub of the deflection pulley through turning. The protective cap can engage in this snap-in groove with a bead, so that a positive-fit connection is created. This, however, involves an expensive solution due to the necessary additional turning process.